Instead of a "leap" occurring from analog video broadcasting to interactive digital television, it has become apparent that the video broadcasting industry is moving in a more gradual fashion. Traditional analog video broadcast services are being first supplemented by digital video broadcast services, then by interactive data services and eventually, by fully interactive multi-media services. Each step in this evolution is being driven by an implementation of a service from which revenue can be generated. For instance, near video-on-demand is now available from digital video servers and enables customers to access concurrently available video presentations.
In present approaches, each of the new digital video services requires reverse channel communication with a head-end or other source of the video broadcast/data.
The growth of Internet services to the home has also fueled interest in interactive services. Digital data broadcasting provides a look and feel of an interactive service on a digital video broadcast platform. Such digital data broadcasting employs a set-top box and the home television receiver to enable a viewing of video images that are sent in MPEG-2 format.
MPEG-2 is a standard established by the Moving Picture Experts Group for digital compression/decompression of motion video and audio. Since up to 10 channels of compressed digital video data can be transmitted over a single six mHz T.V. channel in the United States and eight mHz in Europe, substantially greater utilization of available transmission spectrum is achieved. The MPEG-2 standard also supports digital video transport and covers multiple resolutions, bit rates and delivery mechanisms. When video still frames are sent over a digital video broadcast system, the MPEG-2 standard enables each video still frame to be compressed to an "I" frame which is received and decompressed by the hardware of the set-top box.
Direct digital data broadcasting has been designed to be an incremental service to be added to existing digital video broadcast services. As long as the set-top box in use in a currently available digital video broadcasting system offers necessary firmware and hardware support, modifications to a digital video broadcast system to implement new services are only required at the head-end. Thus, the presently available digital data broadcast system is able to provide a platform for interactive services, without requiring substantial upgrades to user end equipment.
The prior art includes a number of teachings of the provision of multi-media/video services over standard T.V. channels. U.S. Pat. No. 5,521,631 to Budow et al. describes an interactive video services system which provides store and forward distribution of digitized video programming. Encoded and compressed digital video signals are transmitted via a satellite link from a centrally located front end to a plurality of establishments. There, the transmitted digital video programming is stored in a video server computer or is transmitted on a real time basis to customers. The system employs operating system updates, digitized menus and advertising graphics and transmits them over the satellite link to the customer servers.
PCT international application WO 96/17396 to Laursen et al. describes a system for providing multi-media data over a network. The system includes distributed client-server computing facilities and a communication network which is asymmetric. More specifically, a reverse direction communication link is much more limited in bandwidth than the forward direction communication link. The system allows applications to be split, such that set-top boxes focus on presentation, while head-end services run in a distributed server complex and provide access to data via messages across a communication interface.
In the European common market, a system known as "Teletext" is provided over video channels and involves a repetitive, cyclic transmission of text data frames. When a user enters an identifier for a selected frame, the television receiver responds to the selection by awaiting the receipt of the selected frame and causing its display on an associated video television set. Another system, i.e., "Pointcast", permits a user to configure information from the Internet for display on a personal computer. Pointcast catalogs information, constructs a profile for the user and then goes to an Internet-attached server to ask for new information in accordance with the profile. The information is updated periodically.
From the above, it can be seen that there are a number of prior art interactive systems which enable the transfer of digital data via the existing digital data broadcasting network to a customer's television set. In general, such services are either fully interactive, requiring the provision of a reverse communication channel between the customer and the head end or, provide a single channel of selectable video data in accordance with an index or other programming guide which is displayed for user review.
It is an object of this invention to employ an existing digital data broadcasting platform to provide video image information to the user and to enable user interaction therewith, without requiring a reverse communication channel to the broadcasting head end.
It is a further object of this invention to utilize a digital data broadcasting system to broadcast multiple channels of cyclically presented video images and to enable rapid user-access to high priority images in the video images.